A combination of genetic, kinetic and biochemical analysis will attempt to test and elaborate the "matrix model" for membrane transport in eucaryotes. Mutants of Neurospora involving the three systems for amino acid transport (Pm N, Pm B and Pm G) appear to represent alterations of the glycoprotein matrix into which fit specific effector molecules. Mutants involving the effector component of the "binary" transport system will be sought and analyzed. Kinetic analysis of the transport relationship between amino acids in particular families (e.g. Pm N) will continue. The regulatory role of nitrogen metabolism in control of the general (Pm G) amino transport system will be studied. Certain "unique" analog (e.g. FPA) resistant mutants will be further studied (e.g. bradytrophs). A mutant deficient in the "inducible" acetate transport system will be studied in relationship to the known metabolic "acetateless" mutants of Neurospora.